1. Field of the Invention
The present invention relates to a holding chuck for a tire-wheel which is equipped with a chatter-suppressing device.
2. Description of the Related Art
When an automobile tire-wheel is machined, the tire-wheel is clamped by a holding chuck, at the center thereof, and mounted on a metal-cutting machine tool. A tire-wheel generally has a relatively large diameter and is fabricated using relatively thin metal plates. Further, when the outer circumference of the tire-wheel is machined, the tire-wheel is gripped at the center thereof by a holding chuck and rotated around its center axis. In this condition, an undesirable chattering (vibration) occurs at the outer circumference of the tire-wheel (i.e., at a rim of the tire-wheel) during machining.
In order to suppress this undesirable chattering, usually, a suppressing device which supports the rim of the tire-wheel during the machining is used.
FIGS. 8 and 9 show a holding chuck for a tire-wheel equipped with a conventional suppressing device.
In FIGS. 8 and 9, reference numeral 51 designates a chuck body of a holding chuck for a tire-wheel. The chuck body 51 is provided with a clamp 53 and stopper face 52. When a tire-wheel W is mounted on the chuck body 51, the stopper face 52 abuts the center disk portion of the tire-wheel W, as shown in FIG. 8, and positions the tire-wheel in the direction parallel to the center axis of the chuck body. When the tire-wheel W is placed on the stopper face 52, the clamp 53 is inserted into a center hole H of the tire-wheel w and grips the same so that the tire-wheel W is aligned to the center axis of the chuck body.
Numeral 54 in FIGS. 8 and 9 designates a chatter-suppressing damper. As shown in the drawings, a plurality of dampers 54 are fitted to a rim of a holding ring 55 at regular intervals. The holding ring 55 is detachably attached to the chuck body 51 by bolts 56. Each of the chatter-suppressing dampers includes a damping rod 58 which is urged by a spring 54 toward the tire-wheel and abuts the rim of a tire-wheel in order to prevent the chattering of the rim of the tire-wheel.
However, in the conventional holding chuck, it is necessary to replace the holding ring 55 with one having a different diameter when the size of the tire-wheel to be mounted on the chuck is changed. In other words, different sets of the holding ring 55 and the dampers 54, each matching the tire-wheel of different size, must be prepared and stored. Since the height of the holding ring is relatively large as can be seen from FIG. 8 and the shape thereof is not flat, it is difficult to stack the holding rings in the storage. Thus, the number of the holding rings to be stored and the shapes thereof make the handling of the holding rings inconvenient.
Further, the width of the rim of the tire-wheel changes in accordance with the size (the diameter) of the tire-wheel. In the conventional holding chuck, since the damping rod 58 of the chatter-suppressing damper 54 is urged to the rim of the tire-wheel by the spring 57, the urging force of the spring 57 changes as the width of the rim of the tire-wheel (i.e., the stroke of the damping rod 58) changes. Thus, when the width of the rim is small, the damping rods 58 are pressed against the rim end E (FIG. 8) with insufficient force. In some cases this results in insufficient chatter-suppressing.
In view of the problems in the related art as set forth above, the objects of the present invention are to provide a holding chuck for a tire-wheel equipped with a chatter-suppressing device which is capable of suppressing the chattering of the tire-wheels of different size without requiring replacement of the holding ring or dampers.
The object as set forth above is achieved by a holding chuck for a tire-wheel with a chatter-suppressing device, according to the present invention, comprising a clamping device inserted into a center hole of a tire-wheel for clamping and holding the wheel in the position aligning a center axis of a holding chuck, a plurality of chatter-suppressing dampers disposed on a plurality of circles concentric with the center axis of the holding chuck, each of the chatter-suppressing dampers being provided with a damping rod extending in the direction parallel to the center axis of the chuck and abutting a rim of the wheel and a damper cover disposed between the rim of the wheel and the chatter-suppressing dampers and fastened to the holding chuck, the damper cover being provided with holes disposed on a circle concentric with the center axis of the chuck and allowing the damping rods of the dampers disposed on only one of the concentric circles matching the concentric circle of the damper cover to extend therethrough and abut the rim of the wheel.
According to the present invention, chatter-suppressing dampers are disposed on the circles concentric with the center axis of the holding chuck. The diameters of the respective circles correspond to the diameters of the tire-wheels of different sizes. Further, although damping rods of all chatter-suppressing dampers are urged towards the rim of the tire-wheel mounted on the holding chuck, the damper cover allows the damping rods of the chatter-suppressing dampers disposed on only one of the concentric circles to pass through the holes of the damper cover and abut the rim of the tire-wheel, i.e., only the damping rod of the chatter-suppressing damper disposed on the circle, the diameter of which matches the size of the tire-wheel mounted on the chuck, are allowed to extend and abut the rim of the tire-wheel. Other damping rods are blocked by the damper cover and do not extend.
Therefore, when the size of the tire-wheel is changed, only the damper cover is required to be replaced with one having a circle of holes matching the size of the tire-wheel. In other words, it is not required to replace the holding ring and chatter-suppressing dampers when the size of the tire-wheel is changed.
The chatter-suppressing damper may be provided with a pneumatic cylinder to extend the damping rod. By urging the damping rod toward the rim of the tire-wheel by air pressure, a uniform force for pressing the damping rod against the rim end of the tire-wheel can be obtained regardless of the size of the tire-wheel and the width of the rim thereof. Thus, a sufficient chatter-suppressing can be obtained regardless of the size of the tire-wheel.